I'm looking at an application where a 112.5 KVA 480pri - 208sec has (2) sets of 400MCM copper cables coming off of the secondary of the transformer and termininag into a 1600A breaker about 200ft away.
I believe this is a violation of 240.31(C) (I believe this is the right referene) in that the secondary protective device rating must not exceed the rated ampacity of the secondary cables. In this case the (2) sets of 400 MCM cables has an ampacity of 670A. So the way I see it, either the cables sizes would have to be increased to allow for greater ampacity or the breaker would have to be changed to a 600A breaker.
Am I correct in my thinking?
I believe this is a violation of 240.31(C) (I believe this is the right referene) in that the secondary protective device rating must not exceed the rated ampacity of the secondary cables. In this case the (2) sets of 400 MCM cables has an ampacity of 670A. So the way I see it, either the cables sizes would have to be increased to allow for greater ampacity or the breaker would have to be changed to a 600A breaker.
Am I correct in my thinking?